Alternating current bell



` July 2.1,"1931.

ALTERNATING CURRENT BELL Filed Sept. 28' 1925 Grier/nga A. F. LAKE 1,815,853

Patented July 2l, :193.1

UNITED sTATEsPATENT OFFICE ALLAN F'. LAKE'OF OAKLAND, CALIFORNIA, A SSIGNOR T0 LAKE MANUFACTURING CO.,

` INC., A CORPORATION minimums Application led September 28, 1925. Serial No. 59,115.

'My invention relates to audible signalling apparatus operated by an alternating electric current.A The primary object of the invention is the provision of an alternating current bell mechanism having means for oscillating a bell striker at a frequency considerably lower than that of the alternating current.

Another object of the invention is the provision of a novel` alternating current bell mechanism, the striker whereof consists of a solenoid having a plural element core.

A further object of the invention is the provision in an alternating current solenoid for audible signalling a paratus, of a mutually attracting separate element core having para-magnetic retarding means between the elements thereof.

A still ,further object of the invention'is 2o the provision in an alternating current solenoid bell striker of means for damping fthe.

oscillatin frequency of a solenoid core.

With t ese and such other objects in View as will be apparent from the description, my invention resides in the novel construction, combination and arrangement of parts hereinafter described and claimed and illustrated in the accompanying drawings of-which Figure 1 is a side elevation of a bell mechanism constructed in accordance with the principles of the invention;

Figure 2 is a fragmentary horizontal section therethrough;

Figure 3 is a fragmentary vertical section e5 through a modified form of mechanism;

Figure 4 is a group perspective of the solenoid core elements.

In detail ythe invention comprises a base 10 having secured'adjacent one end thereof the short arm 11 of an L-shaped bracket the long arm 12 of which extends upwardly from the base and is apertured to receive therethrough the external threaded end of a brass tube 13. Spaced inwardly from the opposite ends of the tube 13 and threaded thereover are insulation disks 14 between which, over the tube 13 is wound the coil 15 of the solenoid. A cap nut 16 disposed over one end of the tube 13 is,l

adapted to clamp the upright arm 12 of the I r," L-shaped supporting bracket against an end disk 14 of the solenoid thereby securing the solenoid in service position.

' The winding l5 of the solenoid may be enclosed within a cylindrical casing` 17 having one end open and closed by the uprightarm 12 of the supporting bracket against whichl the casing is forced. The opposite end 18 of the casing is closed and provided with a central aperture whereby the casing is applied over the tube 13, being retained in position by means of a cap nut 19 threaded over the opposite end of the tube 13 which projects beyond and through the end 18 of the casing. lt will be a parent that upon tightening the cap nut 19 t e casing ismoved longitudinally over the solenoid to force itsl open end into engagement against the arm 12 of the supporting bracket to provide a complete ein closure vfor the solenoid.

- The ca nut 19 is formed with a central circular o're 2O extending therethrough, through which bore is guided a bronze striker arm 21 having at its inner end an enlarged head 22 slidable within the tube 13 and normally retracted within the solenoid by expansion of a coil spring 23 surrounding the striker arm 21 between the head 22 and cap nut 19. @n being projected fromjthe coil of the solenoid the striker arm 21 is adapted to contact against a bell 24 or other suitable sounding mechanism, carried by a supporting post 25 mounted on the end of the base 10. opposite the supporting bracket.

The core of the solenoid consists of a plurality of elements normally held in spaced relation within the tube/13. These elements comprise a cylinder 26 of soft iron disposed within the tube 13 adjacent the head 22 of the striker arm for free longitudinal movement within the tube, and a c lindrical soft iron pole piece 27 having a re uced shank 28 extending therefrom in the direction of the central core element 26. The soft iron core pieces 26 and 27 are maintained in spaced Y relation by means of a relatively heavy steel e coil expansion spring 29 surrounding the shank 28 between the two core pieces. The spring 29 being of steel is para-magnetic and "assists in the completion of a magnetic path through thecore of the solenoid while at the same time, due to its expansion, resisting the internal movement of th'e core section 27 whereby the oscillatory movement of the separate elements of the core is dampened. The '5 striker arm 21 and head 22 being of bronze are not affected by the magnetic flux within'` the solenoid.

Under ordinary conditions an alternating current solenoid provided with a unitary core piece, would be of no effect in the operation of a bell due to the fact that the core of the solenoid would oscillate at the frequency of the current which is normally 60 cycles. This frequency is too great to permit the proper bell vibration and would result mere'- ly in the production of a buzzing` sound. In the present invention when the winding is energized by one-half cycle of an alternating current, the soft iron core piece 27 together with the'steel spring 29 are pulled inwardly toward the center of the solenoid, acting to throw the core piece 26 against the head 22, the force of the blow being sufiicient to project the striker arm 21 into contact withthe bell 24. As the current drops toward Zero the springs 23 and 29 expand rapidly, reacting from the sudden compression, and the eX- pansion carries'the head 27 of the lunger -to its limit of outward travel. Be ore the.

expansion movement of the springs has been completed the other side of the current energizes the coil but the inward movement of lplunger 28 is resisted and checked by the eX- pansive action of the springs as stated. Before the check thus' imparted can be'overcome, the current` again drops to zero, and `consequently no striking action will have occurred. llVhen the current next rises in value, the expansion action of the springs will have been expended and the core 28 will be drawn inwardly to again perform the striking action as first stated. Thus the frequency of operation of the striker is less than the freeuency of the current, and the speed of action of the striker is so reduced that' a proper tone may be produced from the bell. This reduced frequency of oscillation of the solenoid core causes the striker arm 21 to move 'in accordance therewith and engage the bell in 'such manner that its proper tone may produced.

In themodied form illustrated in Fig-i4 ure 3, the supporting bracket is dispensed.

ani/sm is theoretical and no assertion is made that it is a positive Iand accurate explanation of what takes place. It is certainthat with the construction as described herein, the mechanism operates as intended and there is a reduced oscillation frequency ofthe striker mechanism relative to the current frequency of the solenoid.v This reduction in the rela. tiveV frequencies is entirely novel and produces results hitherto impossible of accomplishment in devices of this class.

While in this illustration of an embodiment of the invention I have described certain details and materials entering into the construction and operation thereof), I'desire it tobe understood that the invention is not to be limited thereby, but that any desired changes and modifications may be made in the details as will fall within the scope of the invention as claimed.

I claim:-

. 1. Invan alternating current solenoid operated signal mechanism, a solenoid, a core 1n the solenoid formed of lineally disposed disconnected members adapted to oscillate under magnetic flux, a spring disposed between said disconnected members in lineal relation thercw ith, a plunger movable in one direction in said core by action of said members, and a spring in said core or moving said plunger in an opposite direction.

2. In an alternating current solenoid operated signal, a solenoid, a sectional core therein. and resilient means movably associated withthe core sections and forming a part .100 thereof 'for reducing the oscillation frequencyof the solenoid core to less than the current frequency.

3. In an alternating current solenoid operated signal mechanism, a solenoid, and a core 105 therein consisting of two movable members of like magnetic characteristics, an expans ion spring between said members, a nonmagneticplunger adjacent one of said menibers, and an expansion spring between a por- 110 tion of said plunger and' one end of the solenoid, said springs cooperating with said members and plunger to retard the oscillating frequency vof the plunger t'o less than the with, together with the cap nut 16 of the pre -v 55 ferred form. In this modification the'solenoid may be -mounted directlg upon the base with one end of the tube 13 eng'closed by one of the' fiber disks 14, the opposite endl beingengagedby the cap nut 19 as in the 60 'preferred form-which supports therethrough.

the striker arm 2 1 having its heady 22 adapted to-be engaged bythe core piece' 26 under action of the steel spring 29 disposed around the shank of the core piece 27.

65 The above described operatlon ofthe mechcurrent frequency.

In testimony whereof I have aiiixed my signature. ALLAN F. LAKE. 

